1. Technical Field
This disclosure relates to a cell culture bag and a method for manufacturing the cell culture bag.
2. Related Art
In a cell culture process for manufacturing, for example, medicines, to maintain conditions optimal to cultivating cells, such as a dissolved oxygen concentration in a culture fluid, pH, a nutrient component concentration, and a culture fluid temperature, measuring these values is important.
As a culture container for cell culture, flasks had been generally used. However, recently, single-use cell culture bags have been widely used. The cell culture bags are commercially available in a state of being sterilized. These cell culture bags feature a simple handling, high permeability to gas, allowing high density culture with good efficiency, or a similar property.
The following describes a measurement of the culture fluid in the cell culture bag with the measurement of the dissolved oxygen concentration as an example with reference to FIG. 12. As a dissolved oxygen concentration sensor, some methods such as an electrode method, a method for using a reagent, and an optical method have been put to practical use. Here, a dissolved oxygen sensor of the optical method has been used.
To optically measure the dissolved oxygen concentration, an oxygen detection sensor chip containing a substance reacting to oxygen is arranged in the culture fluid. Then, excitation light is irradiated to the sensor chip. A phosphorescence emitted from the sensor chip at this moment is observed. The higher dissolved oxygen concentration delays a phase of the phosphorescence more than a phase of the excitation light, and the strength of the phosphorescence reduces. Therefore, modulating the excitation light to be irradiated with, for example, sine wave, allows measuring the phase delay or the strength of the phosphorescence to be observed. Thus, the dissolved oxygen concentration in the culture fluid can be obtained.
In the drawing, a cell culture bag 310 houses a culture fluid 320 which is a culture medium. The cell culture bag 310 uses a stirring blade 330 to uniform an oxygen concentration distribution or a similar distribution in the culture fluid 320. A motor rotates the stirring blade 330 at a predetermined rotation speed.
To the inside of the cell culture bag 310, an oxygen detection sensor chip 340 is attached. An optical system dissolved oxygen sensor 350 includes a signal processing unit 351 and an optical system 352. The optical system 352 includes an excitation optical system and a receiving optical system. The excitation optical system irradiates the excitation light modulated with, for example, the sine wave on the sensor chip 340. The receiving optical system receives the phosphorescence emitted by the sensor chip 340 and converts the phosphorescence into an electrical signal. The signal processing unit 351 performs a predetermined signal process on the electrical signal which is obtained from the receiving optical system. This converts the received phosphorescence into the electrical signal corresponding to an oxygen concentration.
FIG. 13 illustrates an exemplary constitution of the cell culture bag 310 near a position where the sensor chip 340 is attached and the sensor chip 340. As illustrated in the drawing, the cell culture bag 310 has a laminated structure. For example, the cell culture bag 310 is constituted so as to be laminated in an order of an ethylene vinyl acetate (EVA) layer 311, an ethyl vinyl alcohol (EVOH) layer 312, and a low-density polyethylene (LDPE) layer 313 from the inside.
The sensor chip 340 includes a reflective film 343 and a light shielding film 344 arranged on one surface of an oxygen-sensitive film 342. The sensor chip 340 is attached to the cell culture bag 310 with an adhesive layer 341. The adhesive layer 341 is formed at the other surface of the oxygen-sensitive film 342.
The oxygen-sensitive film 342 is a photo-excited substance having, for example, oxygen quenching properties. As such photo-excited substance, a metalloporphyrin complex or a similar complex can be used. The reflective film 343 is used to reflect the excitation light to return this excitation light to the oxygen-sensitive film 342. Thus, the excitation light can be effectively utilized. The light shielding film 344 is used to prevent unwanted external light from entering the optical system 352.
Documents that disclose the related arts regarding the cell culture bag are, for example, JP-A-2009-222429, JP-A-2010-136628, Japanese Patent No. 2628406, Japanese Patent No. 3109740, and U.S. Pat. No. 2,012,171,760 descriptions.